In the game of golf, club design has evolved such that specialized clubs are used to play the ball under a variety of different conditions. Specifically, woods are used off the tee and for long fairway shots with clean lies. Irons are used for intermediate range shots with a variety of trajectories. Wedges are used in close around the green and for playing out of sand and "problem" lies. Putters are typically used on the green.
Wedges are designed to play a ball from a variety of different types of lies in close to the green. Typically, they have club face loft angles of between 48.degree. and 65.degree. to provide a high, arcing trajectory to the ball--the higher the loft angle, the higher the trajectory of the ball. The wedge market is characterized, in general, by much more subtle differences between the products than is generally found in comparisons between various putters and irons. Typically, the sole portion of a wedge is designed with bounce--that is, a downward or descending angle between the leading edge where the face meets the sole and the lowest point on the sole. For example, typical prior art sand wedges as set forth in FIGS. 1 and 2 feature either a straight sole (FIG. 1) or a sole with a radius portion (FIG. 2). Here, bounce will be defined as the angle the sole or any portion thereof makes between a plane thereof and a line perpendicular to the vertical axis of the club as defined by the shaft of the club. This is more clearly set forth in FIG. 3a. The prior art has heretofore disclosed wedges with sole configurations that comprise a single beveled surface between the leading edge and the trailing edge, which surface has a positive bounce angle (see FIG. 1). Occasionally, all or a portion of this beveled surface may be radiused (see FIG. 2). Still, however, the positive bounce angle remains. Additional sole configurations include that found in U.S. Pat. No. 3,897,065 (Karsten Solheim, 1975). The Solheim sole configuration provides for two beveled surfaces defining an intermediate ridge therebetween. However, while the leading edge portion defines a positive bounce angle, the trailing edge portion provides a negative bounce angle. Additionally, U.S. Pat. No. 4,854,580 (Kobayashi, 1989) discloses a sole configuration with two beveled surfaces--again with a leading edge portion having a positive bounce angle and the trailing edge portion having a negative bounce angle.
The function of bounce is to help the club rebound off the surface on which the golf ball lies. To look at it another way, bounce is to help prevent the leading edge of the club face from digging into the surface on which the golf ball lies, with the resultant loss of force and control. The manner in which this is effected can be seen by reference to FIGS. 1 and 2 which represent prior art. As Applicant defines bounce, it can be seen that both figures illustrate club heads that have positive bounce angles. As the golf club passes through the arc of its swing and the leading edge undercuts the ball, the sole will strike the ground. With a positive bounce angle, the resultant force will urge the club head upward to create a "bounce" off the surface. This action helps prevent the face of the club head digging into the turf with the resulting muffed shot and huge divot torn asunder. However, a paradox exists with sand wedges and the like, in that while bounce helps prevent the wedge from digging in the sand, thereby making it easier to play these shots, it also raises the leading edge of the wedge with respect to the centerline of the ball thus making it more difficult to play tight or close lies from outside of sand traps.
Thus, Applicant's design criteria is to provide for a sole design which places the leading edge as low as possible to the horizontal (and thus provide for easier play from tight lies) but which offers plenty of bounce when playing from sand or lush turf, where maximum bounce is desired.
In addition to providing a sole configuration with plenty of bounce but a low leading edge, Applicant's dual bounce sole configuration allows for a narrow sole. This allows for redistribution of weight so as to raise the center of gravity of the club head.